TEST OF PRACTICAL KNOWLEDGE QUESTION
Study Specimens P, Q and R and answer questions 4(a) to 4(d).
(a) Use the information below to complete the following table. (i) Add two drops of specimen P into a beaker containing water, leave it undisturbed and note the time it completely disperses in water. (ii) Add a leveled teaspoonful of specimen Q into another beaker containing water, stir for one second and note the time it takes to completely dissolve. (iii) Cut open specimen R and note the time the odor was perceived. (iv) Give the medium of spread for each of the tests in 4(a)(i) to 4(a) i).
(v) Name the sense organ in humans involved in each of the observations in 4(a)(i) to 4(a)(iii).
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Test |
Observation time(sec) |
Medium of spread |
sense organ |
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(b) Name the biological phenomenon that occurred in 4(a)(iii).
(c) State two factors each that will increase the rate of the phenomenon named in 4(b) for each of the activities in 4(a)(i). (ii) and (iii)
(i) _____________ (ii) _____________ (iii) _____________
(d) Gently place your thumb on the inked stamp pad provided. (i) Neatly thumbprint clearly showing the pattern in the box below.
(ii) Name the type of pattern in the fingerprint in 4(e)(i).
(iii) List three other types of fingerprints. (iv) State three advantages of fingerprints.
(v) What type of variation is fingerprint?
Specimen P is a coloured drop (ink/dye) that spreads in water, Q is a soluble solid (sugar or salt) that dissolves in water, and R is a cut object (such as an onion) whose odour spreads through air. The completed table reflects this.
(a) Completed table
| Specimen | Test | Observation time (sec) | Medium of spread | Sense organ |
|---|
| P | Two drops added to water and left undisturbed until it disperses | About 120 | Liquid (water) | Eye (sight) |
| Q | A level teaspoon added to water, stirred once, timed until dissolved | About 40 | Liquid (water) | Eye (sight) |
| R | Cut open and timed until the odour is perceived | About 5 | Gas (air) | Nose (smell) |
(The exact times depend on the actual observation; the values above are typical.)
(b) Biological phenomenon in 4(a)(iii): Diffusion (the spreading of the odour molecules from a region of higher concentration to a region of lower concentration through the air).
(c) Two factors that increase the rate of the phenomenon in each activity
- (i) P (dispersal in water): increase in temperature; steeper concentration difference (more coloured drops); smaller particle size.
- (ii) Q (dissolving in water): increase in temperature; stirring/agitation; smaller particle size (finer powder).
- (iii) R (odour spreading in air): increase in temperature; movement of air (wind/draught); higher concentration of the odour.
(d) Fingerprints
- (ii) Type of pattern: a loop (typical thumbprint pattern).
- (iii) Three other types of fingerprints: whorl, arch and composite (mixed) patterns.
- (iv) Three advantages of fingerprints: they are unique to each individual and so are used for identification; they are useful in crime detection (forensic evidence); they are used for security and access (biometric verification) and do not change throughout life.
- (v) Type of variation: discontinuous variation (fingerprints fall into distinct pattern classes).
Specimen P is a coloured drop (ink/dye) that spreads in water, Q is a soluble solid (sugar or salt) that dissolves in water, and R is a cut object (such as an onion) whose odour spreads through air. The completed table reflects this.
(a) Completed table
| Specimen | Test | Observation time (sec) | Medium of spread | Sense organ |
|---|
| P | Two drops added to water and left undisturbed until it disperses | About 120 | Liquid (water) | Eye (sight) |
| Q | A level teaspoon added to water, stirred once, timed until dissolved | About 40 | Liquid (water) | Eye (sight) |
| R | Cut open and timed until the odour is perceived | About 5 | Gas (air) | Nose (smell) |
(The exact times depend on the actual observation; the values above are typical.)
(b) Biological phenomenon in 4(a)(iii): Diffusion (the spreading of the odour molecules from a region of higher concentration to a region of lower concentration through the air).
(c) Two factors that increase the rate of the phenomenon in each activity
- (i) P (dispersal in water): increase in temperature; steeper concentration difference (more coloured drops); smaller particle size.
- (ii) Q (dissolving in water): increase in temperature; stirring/agitation; smaller particle size (finer powder).
- (iii) R (odour spreading in air): increase in temperature; movement of air (wind/draught); higher concentration of the odour.
(d) Fingerprints
- (ii) Type of pattern: a loop (typical thumbprint pattern).
- (iii) Three other types of fingerprints: whorl, arch and composite (mixed) patterns.
- (iv) Three advantages of fingerprints: they are unique to each individual and so are used for identification; they are useful in crime detection (forensic evidence); they are used for security and access (biometric verification) and do not change throughout life.
- (v) Type of variation: discontinuous variation (fingerprints fall into distinct pattern classes).
